Part IV of "North & South: Book II" Wednesday night registered a 22.9 Nielsen rating and a 36 percent audience share, as the ABC mini-series easily beat "Blues Lightning" on CBS and the combination of "Blacke's Magic" and "St. Elsewhere" on NBC over the same two hours . . .

After four nights, "Book II" is off about 18 percent in total audience from the first four nights of "North and South I" last November . . .

That's a drop that pretty much reflects the total national TV audience falloff between a cold week in November and the beginning of daylight-saving time in May . . .

However, in comparing the first four nights, there's been a drop of 13 percent in the audience share (38 to 33) from last November, and that's the difference between a hit and an expensive near-miss . . .

Also on Wednesday night, the second outing of CBS' "West 57th" registered an 8.0/14, a bare one-share-point improvement over its debut . . .

Cheering the West 57thers, despite the report card, is word that more than 200 calls and letters have come into CBS seeking to adopt or offering financial help for the education and general well-being of little Anthony, the near street waif from Chicago profiled on the first program . . .

CBS is looking for a responsible organization in Chicago to help follow through on the pledges, which even include a summer on a farm for Anthony . . .

Fox Broadcasting Co., which earlier this week announced that Joan Rivers would start a late-night talk show next fall as an initial step toward the building of a fourth network . . . yesterday announced its first primetime programming effort . . .

It will be a weekly half-hour sitcom called "Down and Out in Beverly Hills," based on the hit movie of the same name . . . which will begin airing next March. Thirteen episodes have been ordered . . .

No cast has been chosen, nor has Fox picked the night on which it will air. The burgeoning network, which already includes Channel 5 here, plans to launch one night of primetime programming each year starting in 1987, as well as additional late-night programs . . .

The series will be produced by Touchstone, the Walt Disney subsidiary that also produces "The Golden Girls" for NBC . . .

Rep. Tim Wirth (D-Colo.), chairman of the House subcommittee on telecommunications, consumer protection and finance, has moved the date for a second hearing on the satellite scrambling issue to June 12 . . .

Wirth said the unavailability of key witnesses caused cancellation of the original May 21 hearings. The development of the backyard satellite dish industry will be on the agenda, as will the furor over the mysterious "Captain Midnight's" recent interruption of the satellite transmission of a Home Box Office movie to complain about scrambling . . .

Daytime Emmys

CBS led the Daytime Emmy nominations announced yesterday with a total of 82, 20 of them for its "As the World Turns" soap opera. . .

The awards, sponsored by the National Academy of Television Arts and Sciences, will be presented on NBC the afternoon of July 17 from the Waldorf-Astoria hotel . . .

In addition to CBS, ABC received 49 nominations, NBC 25, PBS 27 and syndicated shows 23 . . . Important categories included:

Outstanding Lead Actress in a Drama Series: Susan Lucci, Erica Kane on "All My Children," ABC; Elizabeth Hubbard, Lucinda Walsh on "As The World Turns"; Peggy McCay, Caroline Brady on "Days of Our Lives," NBC; Kim Zimmer, Reva Shaykne Lewis on "The Guiding Light," CBS; and Erika Slezak, Victoria Lord Buchanan on "One Life to Live," ABC . . .

Outstanding Lead Actor in a Drama Series: David Canary, Adam Chandler on "All My Children"; Scott Bryce, Craig Montgomery on "As the World Turns"; Larry Bryggman, Dr. John Dixon on "As the World Turns"; Robert S. Woods, Bo Buchanan on "One Life to Live"; Nicholas Coster, Lionel Lockridge on "Santa Barbara," NBC; and Terry Lester, Jack Abbott on "The Young and the Restless" . . .

Outstanding Supporting Actress: Eileen Hurley, Myrtle Fargate on "All My Children"; Kathleen Widdoes, Emma Snyder on "As the World Turns"; Leann Hunley, Anna Brady on "Days of Our Lives"; Uta Hagen, Hortense on "One Life to Live"; and Dame Judith Anderson, Minx Lockridge on "Santa Barbara" . . .

Outstanding Supporting Actor: Louis Edmonds, Langley Wallingford on "All My Children"; Gregg Marx, Tom Hughes on "As the World Turns"; John Wesley Shipp, Douglas Cummings on "As the World Turns"; Larry Gates, H.B. Lewis on "The Guiding Light," CBS; and Al Freeman Jr., Capt. Ed Hall on "One Life to Live" . . .

Outstanding Drama Series: "All My Children"; "As the World Turns"; "General Hospital," ABC; and "The Young and the Restless" . . .

Outstanding Game Show: "Family Feud," ABC; "Jeopardy!," syndicated; "The Price Is Right," CBS; "$25,000 Pyramid," CBS; and "Wheel of Fortune," NBC . . .

We'll have the rest of the key nominations on Monday, TV Column fans. Promise! . . .

NBC's "Today" show recorded a 5.2 Nielsen rating and a 25 percent audience share the week ending May 2, to score its 20th morning win in the past 21 weeks . . .

ABC's "Good Morning America" was second with a 4.9/24 and "CBS Morning News" trailed with a 3.3/16, although that 16 share was CBS' highest since August . . .

Meanwhile, "CBS Evening News With Dan Rather" won the network news race last week with a 12.3 rating and a 24 share . . .

"NBC Nightly News With Tom Brokaw" was second with an 11.9/24, followed by "ABC World News Tonight With Peter Jennings" at 10.3/20 . . .

Now don't jump out of your house slippers, but that 24 percent share of the early-evening audience was NBC News' highest since December 1981, and NBC's four-share-point margin over ABC was its largest over same since April 1980 . . .

Meanwhile, NBC was tying first-place CBS in audience share for the third time in the past five weeks. Which probably explains why CBS confused the sound of so many of you (despite our warning) landing barefoot on your breakfast nook floors after jumping out of your house slippers with the sound of NBC News footsteps . . .

Also in the News

Among the 12 American journalists named yesterday by the Nieman Foundation at Harvard University to the 49th Class of Nieman Fellows:

Ira Rosen, 32, a Washington producer with CBS News' "60 Minutes," who will pursue Middle Eastern studies and world environmental issues during his year at Harvard . . .

A week from tonight (May 16) there will be a benefit -- open to the public -- at Duke Zeibert's restaurant for the Broadcasters' Child Development Center and the local chapter of the National Academy of Television Arts and Sciences . . .

Hours are 6 to 11 p.m. . . .

The center is a nonprofit day-care center serving the Washington metro community and the broadcast industry . . .

A veritable Who's Who of local broadcasting figures will be there to elbow you aside at the buffet and open bar . . .

Hosts will be WRC's Arch Campbell, Channel 7's (and The Post's) Bob Levey and Q107's Elliott and Woodside. Entertainment by the celebrated Capitol Steps . . .

A reel of local TV bloopers has been prepared for viewing, and there will be a raffle of a trip to Hollywood to see "The Tonight Show" and "Cheers" and a trip to New York to watch a live broadcast of the "Today" show have breakfast with Willard Scott . . .

The broadcasters are alsopeddling a new cookbook, called TV dinners and Other Media Munchies," which they'll autograph if you're real nice . . . .

Tickets are $20 in advance, $25 at the door. For ticket information call 587-3993. That's 587-3993.